    function isJSON_test(str) {
            if (typeof str == 'string') {
                try {
                    var obj = JSON.parse(str);
                    console.log('转换成功：' + obj);
                    return true;
                } catch (e) {
                    console.log('error：' + str + '!!!' + e);
                    return false;
                }

            }
            console.log('It is not a string!')
        }
        console.log(isJSON_test('["1","2"]'));  //true
        console.log(isJSON_test('{name:"123"}')); //false
        console.log(isJSON_test('aaaa'));   //false

